Keeping Wood Tight to the Moulder Fence

Advice on moulder setup to keep wide stock from drifting away from the fence during operation. December 27, 2008

We have a Weinig Unimat Gold 6 head moulder. We have been having issues with wider lumber travelling away from the fence. We have checked out operating manual and it says if this is happening it may be due to the infeed wheels not being centered over the wood. So, we have made sure we have the feed wheels centered over the wood but we are still having problems.

We have confirmed a 3 degree cant on our shafts that the infeed rollers are mounted to; this cant is supposed to keep the wood tight to the fence but yet it wanders. Does anyone have any suggestions?

Forum Responses
(Architectural Woodworking Forum)
From contributor B:
My first place to look would be the right side heads. Make sure the cutters are inline with the outfeed fence. We did not like the left side fences on our Profimat so we made a new beefy fence which bolted to the table after the last head. By keeping all of the left side fences fairly tight you should not have a problem.

From contributor R:
Make sure the feed wheels are not on backwards, they will push the wood away if not. As contributor B noted the right side cutter must be in line with the outfeed fence, but also check behind the same fence and make sure there is no debris trapped there which would cause a misalignment. Check the infeed fence for proper alignment. Is the wood ripped straight going in?

From the original questioner:
Thanks for the response. We will keep that in mind. We do though always set the right head with a straight edge to the outfeed fence.

We were taught by Weinig during our in-house training to use the reading of the head from our ATS Measuring stand; we have found however it is much more accurate to set the radial axis of the right head by using a straight edge to the outfeed fence. We do the same thing on the last bottom head if we have our 20 thou shim in. We raise the last bottom head just until it barely scrapes the straight edge so we know it is perfectly lined up with the table.

Also, I couldn't agree more with your thoughts on the left fence; we hate ourís and have thought right from the get-go that we need to re-design something much better than that. It has also been mangled a few times; if it is not out far enough and the new piece of stock coming through catches on it, it bends it like a pretzel! But what is strange is that that happens but then at other times the piece of wood sticks and you can't make it go through the moulder. We have had the machine in operation since August 2007; we have learned a lot but still have more to learn I am sure.

One thing I have noticed is that the most difficult challenge in moulder operation is the balancing act between the pressure system and the feed system. If you have too much pressure (to overcome chatter) then the pieces get stuck; if you don't have less pressure (to overcome feeding issues) you get chatter.
Thanks again so much for your post!

From the original questioner:
Thanks contributor R for your input. We were told by Weinig the proper way the steel infeed rollers are suppose to be and always make sure they are on that way. (I sometimes wonder if we should try them the other way though since we have this problem from time to time). We will check to make sure there is no debris behind the outfeed fence as per your suggestion.

We have had to take a mason string line and stretch it through the moulder twice now to re-align the infeed fence of the moulder, the one that we move in and out during operation. It seems if that thing is not lined up perfectly you have huge problems with the wood travelling away.

We use this masons string line because we do not have a large straight edge. It does seem to work.
Regarding the straightness of the boards, we do joint one edge of the boards first then we rip them 1/4" to 5/16" over the finished width. We generally have the crown out so that the Unimat can straighten the boards as they go in; from what I understand the moulder acts as a jointer as well to straighten the pieces as they go in. To answer your question though for the most part our blanks are relatively straight going in.

From contributor J:
I donít know anything about how the Weinig works but on our Martin T90 whenever stock comes away from the fence itís because the reference engraver insert knives on the right side of the bottom head are trashed or dull.

From contributor U:
Contributor R brings up a great point, make sure the feed rollers are not on backwards. This is how you can tell, look at the top of the roller when on the machine, standing in front of it, the design is like a laying down "L" the short part of the "L" should be toward the outfeed part of the machine, like contributor R said if on backwards the wood will pull away from the fence. Weinig also offers extension shafts for certain types of feed systems that bolt on and bring the rollers out more. I donít know if this is an option for your machine or not.

From the original questioner:
Thanks for the input contributor U. By the way you describe the proper way of installing the steel infeed rollers, it makes me wonder if we were taught wrong. We were taught that when looking at the steel wheel from the side, it kind of looks like a chair; that is each sharp part of the roller. We were told that if we think of each sharp part as a chair, then the back of the chair should be facing the infeed direction of the machine.

As per your example, it would seem that the "L" would be lying down with the long part laying and the short part pointing straight up. As the rollers turn clockwise, then the short part of the "L" would get to the wood before the long part of the "L". Is this correct?

From contributor U:
Yes you are correct, the short part hits first and grabbing on to the lumber and the long part of the "L" keeps it from digging in too deep causing damage to the finish product. Max penetration is 1/8" for this standard roller. The inside diameter of the wheel is a bit smaller that the outside diameter as well to help aid in the theory of pushing it toward the fence, but as contributor R said before, put them on backwards and it works against you.

From contributor U:
Look at the bolt on one in front of the left spindle it can only go on one way. Then make the rest the same way. Mark or color them for quick reference in the future.